<p> Fractionations of C^13/C^12, O^18/O^16 ratios and Mg between coexisting dolomite and calcite have been determined from rocks of a variety of metamorphic grades in Vermont and the Grenville of Ontario. Working criteria for equilibrium are established. Temperature dependent fractionation expressions are derived (1) for O^18 and C^13 from the C-and
O-isotope fractionations concordant with the Mg-calcite solvus thermometer, for T = 130° to 550°C, using natural dolomite-calcite assemblages; (2) for C^13 from hydrothermal partial exchange experiments. Problems with partial exchange reactions are discussed. A thermodynamic analysis of the solvus relations shows that spinodal decomposition probably is
important in high Mg-calcites. Quench phenomena in high grade assemblages are complex. The quench temperature may be much lower than the maximum temperature attained. The sizes of some equilibrium systems are delineated.</p> / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/20163 |
| Date | 07 1900 |
| Creators | Sheppard, Simon Mark Foster |
| Contributors | Schwarcz, H. P., Geochemistry |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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